Let's break this down. We're going to add 674 and 377 together.

Step 1: We'll start by adding the digits 4 & 7 in column 1 and get 11.
We'll write down the last digit 1 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 7 & 7 in column 2 and get 15.
We'll write down the last digit 5 and carry the 1 to the next column.

Step 3: We'll start by adding the digits 6 & 3 in column 3 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

So, 674 + 377 = 1051.

